The present invention relates to a device for cooling a salient-type rotor of a rotary machine such as a synchronous machine by ventilation.
A conventional device for cooling a salient-type rotor of a synchronous machine by ventilation is shown in the vertical section view of FIG. 1 and in the horizontal section view of FIG. 2. These drawings show a vertical-shaft rotary machine, in which reference numeral 1 denotes a rotary shaft, reference numeral 2 denotes a rotor spider, reference numeral 3 denotes a rim which is inserted and secured into the rotor spider and which forms a yoke of the rotor and reference numeral 4 denotes a plurality of ventilation ducts formed in the rim in the radial direction of which the ventilation gap is defined by a plurality of duct pieces 5 and spacer rings 6. Reference numeral 7 denotes bolts for fastening the rim 3, reference numeral 8 denotes nuts, reference numeral 9 denotes a plurality of salient magnetic cores which are made up of a laminate of thin steel plates, which are fastened together by bolts 10, and which are fastened to the outer periphery of the rim 3, reference numeral 11 denotes field coils fitted to the magnetic cores, and reference numeral 12 denotes a fan mounted on the rim 3.
When the rotor rotates, the fan 12 directs the cooling air as indicated by arrow A to cool end portions of the field coils 11, whereby part of the cooling air flows among the field coils 11 as indicated by arrow B, and another part of the cooling air flows through the ends of the stator coils (not shown) as indicated by arrow C to cool them. Further, the cooling air which has entered into the inner side of the rotor spider 2 flows through the ventilation ducts 4 as indicated by arrows D, and flows through the neighboring field coils 11 as indicated by arrows E to cool them. Being assisted by the function of the fan, the cooling air flowing through the field coils 11 passes through ventilation ducts of the stator via air gap G, thereby to cool the stator coils and the stator cores (which are not shown).
In the above-mentioned conventional ventilation cooling device, peripheries of the field coils 11 all face the magnetic cores 9 and are poorly cooled. Further, flow of the cooling air through ventilation ducts 4 in the rim 3 is hindered by the narrowness of the space along the flow path at the lower portions of the neighboring field coils 11. Therefore, ventilation resistance is increased, the blowing amount of cooling air blown through the field coils and ventilation ducts is decreased, and the stator coils and the stator cores are not sufficiently cooled.